[PATCH v3 0/3] enable eeprom "size" property and runtime pm

[PATCH v3 0/3] enable eeprom "size" property and runtime pm

[Divagar Mohandass]

This series adds support for eeprom "size" property which will be read by the
driver for eeprom size. The existing ACPI has a different default size which
can be overridden with a DSD property value provided by the platform FW.

This series also adds support for runtime PM. The eeprom driver currently
did not have support for runtime PM and the device was kept in D0 throughout.

[v1]
- Add support for eeprom "size" property.
- Add runtime PM support to the driver.

[v2]
- Improved the patch subject.

[v3]
- Addressed comments from Sakari Ailus.
- Improved patch description.
- Improved pm support patch.

Divagar Mohandass (3):
  dt-bindings: add eeprom "size" property
  eeprom: at24: add support to fetch eeprom device property "size"
  eeprom: at24: enable runtime pm support

 .../devicetree/bindings/eeprom/eeprom.txt          |  2 +
 drivers/misc/eeprom/at24.c                         | 43 ++++++++++++++++++++++
 2 files changed, 45 insertions(+)

-- 
1.9.1

[PATCH v3 1/3] dt-bindings: add eeprom "size" property

[Divagar Mohandass]

This adds eeprom "size" as optional property for i2c eeproms.
The "size" property allows explicitly specifying the size of the
EEPROM chip in bytes.

Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
---
 Documentation/devicetree/bindings/eeprom/eeprom.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/eeprom/eeprom.txt b/Documentation/devicetree/bindings/eeprom/eeprom.txt
index 5696eb5..1436569 100644
--- a/Documentation/devicetree/bindings/eeprom/eeprom.txt
+++ b/Documentation/devicetree/bindings/eeprom/eeprom.txt
@@ -32,6 +32,8 @@ Optional properties:
 
   - read-only: this parameterless property disables writes to the eeprom
 
+  - size: total eeprom size in bytes
+
 Example:
 
 eeprom@52 {
-- 
1.9.1

[PATCH v3 2/3] eeprom: at24: add support to fetch eeprom device property "size"

[Divagar Mohandass]

Obtain the size of the EEPROM chip from DT if the "size" property is
specified for the device.

Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
---
 drivers/misc/eeprom/at24.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 764ff5df..2199c42 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -570,6 +570,10 @@ static void at24_get_pdata(struct device *dev, struct at24_platform_data *chip)
 	if (device_property_present(dev, "read-only"))
 		chip->flags |= AT24_FLAG_READONLY;
 
+	err = device_property_read_u32(dev, "size", &val);
+	if (!err)
+		chip->byte_len = val;
+
 	err = device_property_read_u32(dev, "pagesize", &val);
 	if (!err) {
 		chip->page_size = val;
-- 
1.9.1

[PATCH v3 3/3] eeprom: at24: enable runtime pm support

[Divagar Mohandass]

Currently the device is kept in D0, there is an opportunity
to save power by enabling runtime pm.

Device can be daisy chained from PMIC and we can't rely on I2C core
for auto resume/suspend. Driver will decide when to resume/suspend.

Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
---
 drivers/misc/eeprom/at24.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 2199c42..a670814 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -24,6 +24,7 @@
 #include <linux/i2c.h>
 #include <linux/nvmem-provider.h>
 #include <linux/platform_data/at24.h>
+#include <linux/pm_runtime.h>
 
 /*
  * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
@@ -501,11 +502,22 @@ static ssize_t at24_eeprom_write_i2c(struct at24_data *at24, const char *buf,
 static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at24_data *at24 = priv;
+	struct i2c_client *client;
 	char *buf = val;
+	int ret;
 
 	if (unlikely(!count))
 		return count;
 
+	client = at24_translate_offset(at24, &off);
+
+	ret = pm_runtime_get_sync(&client->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(&client->dev);
+		pm_runtime_put(&client->dev);
+		return ret;
+	}
+
 	/*
 	 * Read data from chip, protecting against concurrent updates
 	 * from this host, but not from other I2C masters.
@@ -527,17 +539,30 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 
 	mutex_unlock(&at24->lock);
 
+	pm_runtime_put(&client->dev);
+
 	return 0;
 }
 
 static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at24_data *at24 = priv;
+	struct i2c_client *client;
 	char *buf = val;
+	int ret;
 
 	if (unlikely(!count))
 		return -EINVAL;
 
+	client = at24_translate_offset(at24, &off);
+
+	ret = pm_runtime_get_sync(&client->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(&client->dev);
+		pm_runtime_put(&client->dev);
+		return ret;
+	}
+
 	/*
 	 * Write data to chip, protecting against concurrent updates
 	 * from this host, but not from other I2C masters.
@@ -559,6 +584,8 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 
 	mutex_unlock(&at24->lock);
 
+	pm_runtime_put(&client->dev);
+
 	return 0;
 }
 
@@ -743,6 +770,15 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
 	i2c_set_clientdata(client, at24);
 
+	/* enable runtime pm */
+	pm_runtime_get_noresume(&client->dev);
+	err = pm_runtime_set_active(&client->dev);
+	if (err < 0)
+		goto err_clients;
+
+	pm_runtime_enable(&client->dev);
+	pm_runtime_put(&client->dev);
+
 	/*
 	 * Perform a one-byte test read to verify that the
 	 * chip is functional.
@@ -810,6 +846,9 @@ static int at24_remove(struct i2c_client *client)
 	for (i = 1; i < at24->num_addresses; i++)
 		i2c_unregister_device(at24->client[i]);
 
+	pm_runtime_disable(&client->dev);
+	pm_runtime_set_suspended(&client->dev);
+
 	return 0;
 }
 
-- 
1.9.1

Re: [PATCH v3 3/3] eeprom: at24: enable runtime pm support

[Sakari Ailus]

Hi Divagar,

Thanks for the update. A few more comments below.

On Wed, Aug 30, 2017 at 09:41:06AM +0530, Divagar Mohandass wrote:
> Currently the device is kept in D0, there is an opportunity
> to save power by enabling runtime pm.
> 
> Device can be daisy chained from PMIC and we can't rely on I2C core
> for auto resume/suspend. Driver will decide when to resume/suspend.
> 
> Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
> ---
>  drivers/misc/eeprom/at24.c | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index 2199c42..a670814 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -24,6 +24,7 @@
>  #include <linux/i2c.h>
>  #include <linux/nvmem-provider.h>
>  #include <linux/platform_data/at24.h>
> +#include <linux/pm_runtime.h>
>  
>  /*
>   * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
> @@ -501,11 +502,22 @@ static ssize_t at24_eeprom_write_i2c(struct at24_data *at24, const char *buf,
>  static int at24_read(void *priv, unsigned int off, void *val, size_t count)
>  {
>  	struct at24_data *at24 = priv;
> +	struct i2c_client *client;
>  	char *buf = val;
> +	int ret;
>  
>  	if (unlikely(!count))
>  		return count;
>  
> +	client = at24_translate_offset(at24, &off);
> +
> +	ret = pm_runtime_get_sync(&client->dev);
> +	if (ret < 0) {
> +		pm_runtime_put_noidle(&client->dev);
> +		pm_runtime_put(&client->dev);

Two puts are too much here. How about dropping this one?

> +		return ret;
> +	}
> +
>  	/*
>  	 * Read data from chip, protecting against concurrent updates
>  	 * from this host, but not from other I2C masters.

If an error happens between the two chunks, you'll need pm_runtime_put(),
too.

> @@ -527,17 +539,30 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
>  
>  	mutex_unlock(&at24->lock);
>  
> +	pm_runtime_put(&client->dev);
> +
>  	return 0;
>  }
>  
>  static int at24_write(void *priv, unsigned int off, void *val, size_t count)
>  {
>  	struct at24_data *at24 = priv;
> +	struct i2c_client *client;
>  	char *buf = val;
> +	int ret;
>  
>  	if (unlikely(!count))
>  		return -EINVAL;
>  
> +	client = at24_translate_offset(at24, &off);
> +
> +	ret = pm_runtime_get_sync(&client->dev);
> +	if (ret < 0) {
> +		pm_runtime_put_noidle(&client->dev);
> +		pm_runtime_put(&client->dev);

Same here.

> +		return ret;
> +	}
> +
>  	/*
>  	 * Write data to chip, protecting against concurrent updates
>  	 * from this host, but not from other I2C masters.

Ditto.

> @@ -559,6 +584,8 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
>  
>  	mutex_unlock(&at24->lock);
>  
> +	pm_runtime_put(&client->dev);
> +
>  	return 0;
>  }
>  
> @@ -743,6 +770,15 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  
>  	i2c_set_clientdata(client, at24);
>  
> +	/* enable runtime pm */
> +	pm_runtime_get_noresume(&client->dev);
> +	err = pm_runtime_set_active(&client->dev);
> +	if (err < 0)
> +		goto err_clients;
> +
> +	pm_runtime_enable(&client->dev);
> +	pm_runtime_put(&client->dev);
> +

You're just about to perform a read here. I believe you should move the
last put after that.

>  	/*
>  	 * Perform a one-byte test read to verify that the
>  	 * chip is functional.
> @@ -810,6 +846,9 @@ static int at24_remove(struct i2c_client *client)
>  	for (i = 1; i < at24->num_addresses; i++)
>  		i2c_unregister_device(at24->client[i]);
>  
> +	pm_runtime_disable(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
> +
>  	return 0;
>  }
>  

-- 
Regards,

Sakari Ailus
e-mail: sakari.ailus@iki.fi

RE: [PATCH v3 3/3] eeprom: at24: enable runtime pm support

[Mohandass, Divagar]

Hi Sakari,

Thanks for your time.
My comments below.

---
^Divagar

>-----Original Message-----
>From: Sakari Ailus [mailto:sakari.ailus@iki.fi]
>Sent: Wednesday, August 30, 2017 1:24 PM
>To: Mohandass, Divagar <divagar.mohandass@intel.com>
>Cc: robh+dt@kernel.org; mark.rutland@arm.com; wsa@the-dreams.de;
>devicetree@vger.kernel.org; linux-i2c@vger.kernel.org; linux-
>kernel@vger.kernel.org; Mani, Rajmohan <rajmohan.mani@intel.com>
>Subject: Re: [PATCH v3 3/3] eeprom: at24: enable runtime pm support
>
>Hi Divagar,
>
>Thanks for the update. A few more comments below.
>
>On Wed, Aug 30, 2017 at 09:41:06AM +0530, Divagar Mohandass wrote:
>> Currently the device is kept in D0, there is an opportunity to save
>> power by enabling runtime pm.
>>
>> Device can be daisy chained from PMIC and we can't rely on I2C core
>> for auto resume/suspend. Driver will decide when to resume/suspend.
>>
>> Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
>> ---
>>  drivers/misc/eeprom/at24.c | 39
>> +++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 39 insertions(+)
>>
>> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
>> index 2199c42..a670814 100644
>> --- a/drivers/misc/eeprom/at24.c
>> +++ b/drivers/misc/eeprom/at24.c
>> @@ -24,6 +24,7 @@
>>  #include <linux/i2c.h>
>>  #include <linux/nvmem-provider.h>
>>  #include <linux/platform_data/at24.h>
>> +#include <linux/pm_runtime.h>
>>
>>  /*
>>   * I2C EEPROMs from most vendors are inexpensive and mostly
>interchangeable.
>> @@ -501,11 +502,22 @@ static ssize_t at24_eeprom_write_i2c(struct
>> at24_data *at24, const char *buf,  static int at24_read(void *priv,
>> unsigned int off, void *val, size_t count)  {
>>  	struct at24_data *at24 = priv;
>> +	struct i2c_client *client;
>>  	char *buf = val;
>> +	int ret;
>>
>>  	if (unlikely(!count))
>>  		return count;
>>
>> +	client = at24_translate_offset(at24, &off);
>> +
>> +	ret = pm_runtime_get_sync(&client->dev);
>> +	if (ret < 0) {
>> +		pm_runtime_put_noidle(&client->dev);
>> +		pm_runtime_put(&client->dev);
>
>Two puts are too much here. How about dropping this one?

Ack
Will fix in next version.

>
>> +		return ret;
>> +	}
>> +
>>  	/*
>>  	 * Read data from chip, protecting against concurrent updates
>>  	 * from this host, but not from other I2C masters.
>
>If an error happens between the two chunks, you'll need pm_runtime_put(),
>too.
>

Ack

>> @@ -527,17 +539,30 @@ static int at24_read(void *priv, unsigned int
>> off, void *val, size_t count)
>>
>>  	mutex_unlock(&at24->lock);
>>
>> +	pm_runtime_put(&client->dev);
>> +
>>  	return 0;
>>  }
>>
>>  static int at24_write(void *priv, unsigned int off, void *val, size_t
>> count)  {
>>  	struct at24_data *at24 = priv;
>> +	struct i2c_client *client;
>>  	char *buf = val;
>> +	int ret;
>>
>>  	if (unlikely(!count))
>>  		return -EINVAL;
>>
>> +	client = at24_translate_offset(at24, &off);
>> +
>> +	ret = pm_runtime_get_sync(&client->dev);
>> +	if (ret < 0) {
>> +		pm_runtime_put_noidle(&client->dev);
>> +		pm_runtime_put(&client->dev);
>
>Same here.
>

Ack

>> +		return ret;
>> +	}
>> +
>>  	/*
>>  	 * Write data to chip, protecting against concurrent updates
>>  	 * from this host, but not from other I2C masters.
>
>Ditto.

Ack

>
>> @@ -559,6 +584,8 @@ static int at24_write(void *priv, unsigned int
>> off, void *val, size_t count)
>>
>>  	mutex_unlock(&at24->lock);
>>
>> +	pm_runtime_put(&client->dev);
>> +
>>  	return 0;
>>  }
>>
>> @@ -743,6 +770,15 @@ static int at24_probe(struct i2c_client *client,
>> const struct i2c_device_id *id)
>>
>>  	i2c_set_clientdata(client, at24);
>>
>> +	/* enable runtime pm */
>> +	pm_runtime_get_noresume(&client->dev);
>> +	err = pm_runtime_set_active(&client->dev);
>> +	if (err < 0)
>> +		goto err_clients;
>> +
>> +	pm_runtime_enable(&client->dev);
>> +	pm_runtime_put(&client->dev);
>> +
>
>You're just about to perform a read here. I believe you should move the last
>put after that.

At the end of at24_read we are performing a pm_runtime_put, still we need this change ?

>
>>  	/*
>>  	 * Perform a one-byte test read to verify that the
>>  	 * chip is functional.
>> @@ -810,6 +846,9 @@ static int at24_remove(struct i2c_client *client)
>>  	for (i = 1; i < at24->num_addresses; i++)
>>  		i2c_unregister_device(at24->client[i]);
>>
>> +	pm_runtime_disable(&client->dev);
>> +	pm_runtime_set_suspended(&client->dev);
>> +
>>  	return 0;
>>  }
>>
>
>--
>Regards,
>
>Sakari Ailus
>e-mail: sakari.ailus@iki.fi

Re: [PATCH v3 3/3] eeprom: at24: enable runtime pm support

[Sakari Ailus]

On Wed, Aug 30, 2017 at 12:32:07PM +0000, Mohandass, Divagar wrote:
> >> @@ -743,6 +770,15 @@ static int at24_probe(struct i2c_client *client,
> >> const struct i2c_device_id *id)
> >>
> >>  	i2c_set_clientdata(client, at24);
> >>
> >> +	/* enable runtime pm */
> >> +	pm_runtime_get_noresume(&client->dev);
> >> +	err = pm_runtime_set_active(&client->dev);
> >> +	if (err < 0)
> >> +		goto err_clients;
> >> +
> >> +	pm_runtime_enable(&client->dev);
> >> +	pm_runtime_put(&client->dev);
> >> +
> >
> >You're just about to perform a read here. I believe you should move the last
> >put after that.
> 
> At the end of at24_read we are performing a pm_runtime_put, still we need this change ?

True, so this isn't an actual problem.

It'll still power the chip down when you're about to need it, so it'd make
sense to perform the check before pm_runtime_put().

I might move the runtime PM setup after the check altogether.

-- 
Sakari Ailus
e-mail: sakari.ailus@iki.fi

Re: [PATCH v3 3/3] eeprom: at24: enable runtime pm support

[Sakari Ailus]

On Wed, Aug 30, 2017 at 12:32:07PM +0000, Mohandass, Divagar wrote:
> >> @@ -743,6 +770,15 @@ static int at24_probe(struct i2c_client *client,
> >> const struct i2c_device_id *id)
> >>
> >>  	i2c_set_clientdata(client, at24);
> >>
> >> +	/* enable runtime pm */
> >> +	pm_runtime_get_noresume(&client->dev);
> >> +	err = pm_runtime_set_active(&client->dev);
> >> +	if (err < 0)
> >> +		goto err_clients;
> >> +
> >> +	pm_runtime_enable(&client->dev);
> >> +	pm_runtime_put(&client->dev);
> >> +
> >
> >You're just about to perform a read here. I believe you should move the last
> >put after that.
> 
> At the end of at24_read we are performing a pm_runtime_put, still we need this change ?

True, so this isn't an actual problem.

It'll still power the chip down when you're about to need it, so it'd make
sense to perform the check before pm_runtime_put().

I might move the runtime PM setup after the check altogether.

-- 
Sakari Ailus
e-mail: sakari.ailus-X3B1VOXEql0@public.gmane.org
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RE: [PATCH v3 3/3] eeprom: at24: enable runtime pm support

[Mohandass, Divagar]

Hi Sakari,

Thanks for the review.
My comments below.

---
^Divagar

>-----Original Message-----
>From: Sakari Ailus [mailto:sakari.ailus@iki.fi]
>Sent: Wednesday, August 30, 2017 6:11 PM
>To: Mohandass, Divagar <divagar.mohandass@intel.com>
>Cc: robh+dt@kernel.org; mark.rutland@arm.com; wsa@the-dreams.de;
>devicetree@vger.kernel.org; linux-i2c@vger.kernel.org; linux-
>kernel@vger.kernel.org; Mani, Rajmohan <rajmohan.mani@intel.com>
>Subject: Re: [PATCH v3 3/3] eeprom: at24: enable runtime pm support
>
>On Wed, Aug 30, 2017 at 12:32:07PM +0000, Mohandass, Divagar wrote:
>> >> @@ -743,6 +770,15 @@ static int at24_probe(struct i2c_client
>> >> *client, const struct i2c_device_id *id)
>> >>
>> >>  	i2c_set_clientdata(client, at24);
>> >>
>> >> +	/* enable runtime pm */
>> >> +	pm_runtime_get_noresume(&client->dev);
>> >> +	err = pm_runtime_set_active(&client->dev);
>> >> +	if (err < 0)
>> >> +		goto err_clients;
>> >> +
>> >> +	pm_runtime_enable(&client->dev);
>> >> +	pm_runtime_put(&client->dev);
>> >> +
>> >
>> >You're just about to perform a read here. I believe you should move
>> >the last put after that.
>>
>> At the end of at24_read we are performing a pm_runtime_put, still we need
>this change ?
>
>True, so this isn't an actual problem.
>
>It'll still power the chip down when you're about to need it, so it'd make sense
>to perform the check before pm_runtime_put().
>
>I might move the runtime PM setup after the check altogether.

Ok, I will move the pm_runtime_put() after the check and publish the v4.
Moving the PM setup altogether below, will introduce more error handling in read call.

>
>--
>Sakari Ailus
>e-mail: sakari.ailus@iki.fi